A PQQ-dependent oxidoreductase in Trypanosoma cruzi reveals a novel redox activity in a eukaryotic pathogen

Trypanosoma cruzi, the etiological agent of Chagas disease, faces profound nutritional and redox stress throughout its life cycle, requiring exceptional metabolic plasticity for survival across insect and mammalian hosts. Despite this, several parasite-specific metabolic pathways remain poorly characterized. Pyrroloquinoline quinone (PQQ)-dependent dehydrogenases are widespread in prokaryotes, where they play crucial roles in the oxidation of various alcohols and sugars. In contrast, their presence in pathogen eukaryotes has remained uncharacterized. Here, we report that the protein Tc323 from T. cruzi is a PQQ-dependent oxidoreductase with conserved structural features and an expanded domain architecture. Computational structural modeling predicted that Tc323 harbors six β-propeller domains, each composed of nine blades, while phylogenetic analyses suggested that this multi-domain architecture originated before the divergence of Trypanosomatidae. Consistent with these predictions, docking simulations revealed high-affinity binding of the PQQ cofactor to all six β-propeller domains, and immunoaffinity-purified Tc323 displayed PQQ-dependent oxidoreductase activity in vitro. Localization studies further showed that Tc323 is a membrane-associated protein that localizes to both the endoplasmic reticulum and glycosomes throughout the parasite life cycle and is also released in extracellular vesicles. Together, these findings uncover a previously unrecognized PQQ-dependent activity in T. cruzi and suggest a novel redox-related enzymatic function that may contribute to parasite adaptation to nutritional and oxidative stress.